Both - I am in control 90% of the time, clearing during/after nebbing. But occasionally I still get coughing fits - usually it feels like a mucus plug is caught in my throat & I stop what I am doing & huff cough until I get rid of it.

@kathyhg - I carry water & "Gin Gin" hard ginger candies - both help to stop a cough when I am out & about unless I have that "stuck" feeling. When I do, I usually excuse myself & cough it out, often in my car. Regular physical activity helps me get the mucus out. This sounds really crazy, because cold air is usually a problem for me, but getting out in the cold and moving help clear my lungs when I go back into the warm. Even a short walk helps.
Sue